[PATCH 05/15] btrfs-progs: remove variable length stack arrays

[Zach Brown <zab@redhat.com>]

sparse hates variable length array definitions on the stack:

 btrfs-show-super.c:155:21: warning: Variable length array is used.

And it's right to.  They're a fragile construct that doesn't handle bad
input well at all.

Signed-off-by: Zach Brown <zab@redhat.com>
---
 btrfs-show-super.c |  2 +-
 volumes.c          | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/btrfs-show-super.c b/btrfs-show-super.c
index c2e844d..0c3c73c 100644
--- a/btrfs-show-super.c
+++ b/btrfs-show-super.c
@@ -152,7 +152,7 @@ static int load_and_dump_sb(char *filename, int fd, u64 sb_bytenr)
 
 static int check_csum_sblock(void *sb, int csum_size)
 {
-	char result[csum_size];
+	char result[BTRFS_CSUM_SIZE];
 	u32 crc = ~(u32)0;
 
 	crc = btrfs_csum_data(NULL, (char *)sb + BTRFS_CSUM_SIZE,
diff --git a/volumes.c b/volumes.c
index e460bce..dba5b0e 100644
--- a/volumes.c
+++ b/volumes.c
@@ -1779,12 +1779,15 @@ int write_raid56_with_parity(struct btrfs_fs_info *info,
 			     struct btrfs_multi_bio *multi,
 			     u64 stripe_len, u64 *raid_map)
 {
-	struct extent_buffer *ebs[multi->num_stripes], *p_eb = NULL, *q_eb = NULL;
+	struct extent_buffer **ebs, *p_eb = NULL, *q_eb = NULL;
 	int i;
 	int j;
 	int ret;
 	int alloc_size = eb->len;
 
+	ebs = kmalloc(sizeof(*ebs) * multi->num_stripes, GFP_NOFS);
+	BUG_ON(!ebs);
+
 	if (stripe_len > alloc_size)
 		alloc_size = stripe_len;
 
@@ -1813,7 +1816,12 @@ int write_raid56_with_parity(struct btrfs_fs_info *info,
 			q_eb = new_eb;
 	}
 	if (q_eb) {
-		void *pointers[multi->num_stripes];
+		void **pointers;
+
+		pointers = kmalloc(sizeof(*pointers) * multi->num_stripes,
+				   GFP_NOFS);
+		BUG_ON(!pointers);
+
 		ebs[multi->num_stripes - 2] = p_eb;
 		ebs[multi->num_stripes - 1] = q_eb;
 
@@ -1821,6 +1829,7 @@ int write_raid56_with_parity(struct btrfs_fs_info *info,
 			pointers[i] = ebs[i]->data;
 
 		raid6_gen_syndrome(multi->num_stripes, stripe_len, pointers);
+		kfree(pointers);
 	} else {
 		ebs[multi->num_stripes - 1] = p_eb;
 		memcpy(p_eb->data, ebs[0]->data, stripe_len);
@@ -1838,5 +1847,8 @@ int write_raid56_with_parity(struct btrfs_fs_info *info,
 		if (ebs[i] != eb)
 			kfree(ebs[i]);
 	}
+
+	kfree(ebs);
+
 	return 0;
 }
-- 
1.7.11.7